Recently, home bleaching has been introduced into the dental health care market for the management of stained teeth. Home bleaching is a technique utilizing weak oxidizing agents such as 6 to 15 percent carbamide peroxide or other peroxy compound which are delivered to the dental arch by the patient using a rigid dental appliance which is custom fabricated by a dentist or dental laboratory. Protocols outlined by dental professionals for the treatment of stained teeth employing the home bleaching technique generally recommend that the patient wear a rigid custom dental appliance for periods of up to 120 minutes per day usually over the course of several weeks, totaling between 20 to 40 hours of home bleaching time.
All currently available bleaching agents are either viscous liquids or gels. Bleaching agents are commercially available and packaged in separate dispensing containers such as bottles, syringes, and tubes. The bleaching agent is self-administered by the patient, who dispenses an estimated quantity of bleaching agent to the rigid custom dental appliance.
The exact origin of the home bleaching procedure is unclear. The earliest reports of this technique occurred in the mid-1960's when two dentists in Arkansas reported Glyoxide.TM., which is commercially available from Marion Merrel Dow, Inc. Glyoxide is an agent used in a custom dental appliance, or dental splint, for soft tissue wound healing, resulted in the desirable side effect of whitening teeth. Glyoxide.TM. is an over-the-counter preparation containing 10% carbamide peroxide in glycerine. These dentists switched to Proxigel.TM., which is commercially available from Reed & Carnrick Pharmacy after its introduction into the over-the-counter market in 1972. Proxigel.TM. is a combination of water, glycerine, Carbopol.TM. (thickening agent) and 10% carbamide peroxide.
The first report of the home bleaching procedure was published in 1989, when Haywood and Heymann reported successful bleaching using Proxigel.TM. in a custom fabricated dental appliance to be worn at night. In the Haywood and Heymann procedure, the bleaching agent was placed in a soft plastic, vacuum formed dental appliance for an average of 7.5 hours per night for 2 to 5 weeks. Also, in 1989, White and Brite.TM., which is marketed by Omni International, became the first commercially available dental bleaching agent specifically for whitening teeth. White and Brite.TM. is a preparation containing 10% carbamide peroxide in glycerine which is sold exclusively to dentists and sold in conjunction with custom-fitted or prescription dental appliances. Since its introduction into the dental health care market, over 20 companies have marketed similar products.
The aforementioned home bleaching techniques require two dental office visits and the fabrication of a rigid custom dental appliance. During the first office visit, impressions of the dental arches are taken, from which rigid custom-fitted dental appliances are fabricated. The use of thermoplastic films are recommended for the fabrication of rigid custom dental appliances which function to carry and deliver various home bleaching agents to the dental arches. Thermoplastic films are sold as rigid or semi-rigid sheeting and are available in various sizes and thicknesses. Some manufacturers also offer laminations of porous foams or low modulus plastics to rigid thermoplastic films.
Fabrication of rigid custom dental appliances to stone models of the dental arches necessitates heating and vacuum forming a rigid thermoplastic sheet to the stone models of a patient's dental arches. The excess sheeting is subsequently removed and the resulting rigid custom dental appliance polished and provided to the dentist for fitting to the patient's dental arches.
Dentists have traditionally utilized one of three types of dental appliances for bleaching teeth. The first type is a rigid appliance which is fitted precisely to the patient's dental arches.
A second type of rigid custom dental appliance frequently practiced by dentists is the delivery of home bleaching agents in an "oversized" rigid custom dental appliance. The dental laboratory fabrication technique for the oversized rigid dental appliance involves augmenting the facial surfaces of the teeth on the stone models with materials such as die spacer or light cured acrylics. Next, thermoplastic sheeting is heated and subsequently vacuum formed around the augmented stone models of the dental arch. The net effect of this method results in an "oversized" rigid custom dental appliance.
A third type of rigid custom dental appliance, which is used with less frequency, is a rigid bilaminated custom dental appliance fabricated from laminations of materials, ranging from soft porous foams to rigid, non-porous films. The non-porous, rigid thermoplastic shells of these bilaminated dental appliances encase and support an internal layer of soft porous foam.
After consultation with the dentist and fabrication of the aforementioned dental appliance, a teeth whitening procedure utilizing the dental appliance is practiced by the patient, who then typically applies the bleaching agent daily. The patient dispenses the home bleaching agent into the rigid custom dental appliance and then places the appliance over the dental arch. Generally, the recommended treatment period ranges from 30 to 120 minutes per day. At the end of the treatment period, the dental appliance is removed, cleaned with water to remove any remaining bleaching agent, and then stored until the next application.
Unfortunately, there exist many problems with obtaining rigid custom-fabricated dental appliances. Such problems include the time and expense of making dental impressions and dental laboratory work, two office visits, and possibly reshaping poorly fitted appliances.
There exist additional drawbacks with custom bilaminated dental devices, including occlusion and retention of bleaching agent. Furthermore, cleaning and maintenance of the foam-lined dental appliance is difficult, due to its high surface area and pore volume.
Yet further problems of oversized rigid custom dental appliance, including, but not limited to, occlusion, increased fabrication time and cost, irritation to the lip of the appliance contacting the gingival region, and decreased retention of the bleaching agent within the target area.
Such problems triggered the development of a fourth and final type of treatment regimen employed to deliver home bleaching. That regimen replaces rigid custom dental appliances with individually packaged disposable U-shaped soft foam trays saturated with a premeasured quantity of bleaching agent. Such a device is commercially available from Cadco Dental Products in Oxnard, Calif. under the tradename VitalWhite.TM.. Recommended treatment protocol described in the product's package insert instructs the patient to fit the device around his or her teeth and to keep the tray in position for sixty minutes after which time it is removed and discarded. Cadco suggests that fourteen sixty minute applications be delivered in a two week period.
Unfortunately, however, foam appliances used in home bleaching systems such as that provided by Cadco have proven to be replete with their own problems. The porous foam tray of such systems is bulky, lacks adequate structural rigidity to fit securely over the dental arches, and causes excessive salivation.
Such foam appliances fail to direct and confine the application of home bleaching agents on the surfaces of a patient's teeth, which is critical to the safety and efficacy of any dental appliance, or other medical device used in or on the human body. Furthermore, the surfaces of such foam devices, which are saturated with bleaching agent, are open and exposed to the oral cavity, and allow the elution of large quantities of bleaching agent from the device, enter the oral cavity, and be ingested by the patient. In addition, because of the discomfort associated with the moisture buildup resulting from foaming of the bleaching agent and salivation, patient compliance and acceptance is low.
Further drawbacks attendant to prior art teeth bleaching methods include hypersensitive reactions, nausea and other untoward side effects resulting. Such side effects may result from application of strong concentrations of bleaching agent to the dental arches of a patient who is unaccustomed to teeth bleaching. To date, no medicinal agents have been derived to alleviate or attenuate such and other contraindications.
Nor have compositions been derived to generally improve the condition of the teeth and mouth, regardless of whether the dentition have been subject to whitening or other of any other dental procedure.
Thus, there exist many problems with devices for delivering home bleaching agents which are presently available. Conventional rigid, custom-fabricated dental appliances require time-consuming and expensive dentist office visits, dental laboratory tests and fitting of each patient's dentition. Furthermore, any changes in the surface of the patient's teeth, such as fillings, crowns, and other accidental or therapeutic alterations of the dentition, would affect the fit of the rigid custom dental appliance and warrant repeating the entire fabrication procedure. Refabrication of the splint may also be required in the event of subsequent rebleaching.
Still further drawbacks with systems utilizing known systems for treatment of dental arches result improper dispensation of agent into dental appliances, particularly when the agent is dispensed by patients who are typically inexperienced and unaware of the importance of precision and infection control when self-administering such agents. As a result of such improper dispensing techniques, bleaching or other medicinal agent is often overfilled, spilled or incorrectly measured. Lack of aseptic technique increases the risk of contaminating the bleaching or other dental agent into an appliance. Patients who are self administering bleaching or other medicinal agents often fail to provide the careful maintenance, cleaning, and storage which is necessary for a rigid custom dental appliance to perform adequately throughout its entire service life.
Yet further problems result from patients' frequent dispersion of excessive bleaching or other medicinal agent into the dental appliance which is subsequently displaced from the appliance into the oral cavity and spilled into the mouth, ingested and introduced into the digestive system. Ingestion of significant amounts of bleaching agent may cause the user great discomfort and hypersensitive reactions. The resulting application of excessive bleaching agent and leakage of bleaching agent from the dental carriers or retainers may also cause gingival irritation, burning, edema, nausea and other allergic reactions. A patient may be thus subjected to excessive quantities of bleaching agent, particularly after the multiple treatments typically required to attain acceptable clinical results.
Moreover, the sponge-like permeability of disposable foam trays merely exacerbated problems of systems utilizing custom dental appliances, including poor retention or confinement of the bleaching agent to the target area and ingestion of the agent. These problems are not exhaustive but are mere examples of difficulties encountered with present devices. Therefore, it is apparent that there is a need for substantial improvement in dental treatments involving application of bleach or other medicinal agents to a patient's dentition and periodontal tissue.